This invention relates to a keyswitch for use primarily in electronic devices such as keyboards, mice, gaming devices, consumer electronics, and the like. In particular, the keyswitch includes a button portion that is secured to a base portion with a lever assembly such that the button portion moves substantially linearly within its housing. Preferably, several keyswitches are integrally molded to a common base portion, forming a monolithic structure that may be quickly and easily manufactured and installed in the electronic device.
Keyswitches are commonly used to command a wide variety of functions. For example, electronic devices, such as keyboards, mice, and gaming devices typically have several keyswitches, or buttons, that a user depresses to activate a wide variety of functions. Modem keyboards not only include keyswitches for commanding individual letters, numbers, and symbols of a traditional typewriter, but also provide one or more additional keyswitches, usually aligned in an upper row of the keyboard, for allowing the user easy access and control of a particular application software, such as an Internet browser. It is desirable for keyswitches to move smoothly and independently from each other.
There are generally two types of keyswitches used on electronic devices. One type of keyswitch is an individually-molded component slideably received in an individually molded housing. These components are assembled onto a base and over an electronic switching device, such as a conventional resilient dome and conductive membrane assembly, or a contact switch. This type of keyswitch slides freely and essentially linearly within its housing providing smooth operation that is independent from other installed keyswitches.
However, because each keyswitch is individually molded and assembled and the typical installation includes multiple keyswitches, tooling costs of manufacturing are high. Moreover, considerable time and labor is required to install the required keyswitches. For example, a typical keyboard may contain 104 such key switches with one assembler responsible for installing between three to forty key switches. Depending on whether the key switch is unique, three unique keys may take the same amount of time to install as would forty identical keys. Accordingly, five to six assemblers may be needed to install these key switches on one keyboard.
Also, engineering adjustments to the keyswitches, such as to fine tune the height of the keyswitches with respect to the keyboard, or to improve the resistance characteristics of the keyswitches, require the design of each individual keyswitch assembly to be modified, significantly increasing the expenses associated with fine-tuning a product containing such keyswitches.
In light of the high tooling, manufacturing, and installation costs associated with individually molded keyswitches, a second, more economical, keyswitch assembly has emerged. This keyswitch assembly includes pivotally securing a button portion of the keyswitch to a base portion through an elongate lever arm. In particular, the button portion is positioned on the end of the lever arm extending from the base such that the button portion may be depressed. This type of keyswitch is commonly referred to in the industry as a lever keyswitch. Several lever keyswitches can be integrally molded to the base portion, thereby saving installation time and molding expenses by allowing all of the keyswitches to be manufactured in one mold, and installed at once by a single installer.
However, the button portions of such known lever keyswitches must move along the arcuate path defined by their respective lever arms. Accordingly, large tolerances in guide openings, or guide sleeves, are required for the button portions to move, thereby compromising their smooth operation. Moreover, in cases where several lever keyswitches are integrally molded together at a base portion, actuating one button portion can inadvertently move the other button portions.
Thus, despite the benefits of known keyswitches, there remains a need for a lever keyswitch that moves smoothly and substantially linearly, and that can also include multiple keyswitches that are integrally molded to a common base portion to form a monolithic structure that may be quickly, easily, and economically installed in an electronic device.
In addition to other benefits that will become apparent in the following disclosure, the present invention fulfills these needs.
The present invention is a lever keyswitch that includes a button portion secured to a base portion with a lever assembly that permits the button portion to move substantially linearly within a sleeve on a case of the electronic device. In particular, the lever assembly includes an elongate, resilient, and preferably U-shaped, lever extending from a base portion and an elongate, resilient, offset member extending from the center of the U-shaped lever to the button portion, which is encircled by the U-shaped lever. The lever and offset member work together to define a synthetic four bar linkage, thereby allowing the button portion to move essentially linearly within the sleeve.
Preferably, the base portion is an elongate spine, and a plurality of lever keyswitches, including their lever assemblies, are secured along that spine. More preferably, the spine and plurality of keyswitches, including their related button portions, levers and offset members are integrally molded of the same material using one mold, resulting in a monolithic structure that may be quickly and easily installed in the electronic device by a single installer.